OVERVIEW
Acute mastitis +/- Abscess Formation
Chronic (Lymphocytic) Mastitis/Diabetic Mastopathy
Granulomatous Inflammation
Fat Necrosis
Acute Mastitis +/- Abscess formation
General Information
Classical signs of inflammation (heat, redness, swelling, painful)
Staph most common cause
Inc PMNs (neutrophils) with intraductal and periductal inflammation
Etiology
Due to a fissure in the skin from breastfeeding that allows for infection of underlying breast.
Often due to Staphylococcus aureus or streptococci (Strep often produces diffuse cellulitis)
Clinical Picture
Usually mom comes in a month after starting breastfeeding with an irritated, inflamed breast.
Can form a firm mass in breast (DDx: CANCER!)
Typically unilateral (affecting the side used for breastfeeding)
If untreated with antibiotics, infection can spread or an abscess can form. (see abscess for more details)
Histology
Lots of neutrophils
Abscess formation= organization with fibrous scar formation around area of infection/neutrophils/pus etc
Differential Diagnosis:
RULE OUT INFLAMMATORY CARCINOMA OF THE BREAST!!!
Chronic Lymphocytic Mastitis (Diabetic Mastopathy)
General
Often presents as a discrete mass in young patients with Type 1 Diabetes
Similar histologic features can be seen in patients with other autoimmune diseases
Ex: Hashimoto's disease; or even in individuals without autoimmune diseases or in men
Histology
Breast tissue with dense keloid-like stromal fibrosis (paucicellular, often glassy in appearance)
Dense lymphocytic infiltrates surrounding lobules, ducts and blood vessels
Lymphocytes are predominantly B-cells (NOTE: there is NO inc risk for lymphoma)
Epithelioid stromal cells (myofibroblasts) with enlarged nuclei and small nucleoli
(Idiopathic) Granulomatous inflammation
General Information:
Most granulomatous inflammatory lesions of the breast are idiopathic.
Often clinically presents as a mass lesion in young females with a history of recent pregnancy.
Histologic findings:
Granulomatous inflammation admixed with neutrophils
A few granulomas show central neutrophilic infiltrate (microabscess)
Caseous necrosis is NOT seen
DDx: Must exclude other causes of granulomatous inflammation (TB, sarcoid, fungal infection etc)
Fat Necrosis
Etiology
Phagocytosis of necrotic adipose cells
Most common cause is trauma (MVC etc.)
Can be seen with duct ectasia that has ruptured (may have apocrine metaplasia present)
Clinical picture
Trauma to breast then patient has a localized, firm area with eventual scarring & calcifications.
Histologic Findings
Histologic Findings:
Consists of necrotic adipocytes, fibrosis and inflammation
Irregular steatocytes with loss of peripheral nuclei
Pink amorphous necrotic material/debris
Inflammatory cells
Foamy (lipid-laden) macrophages
+/- Foreign body giant cells
Neutrophils/lymphocytes/plasma cells
BEWARE: Reactive fibroblasts and reactive endothelial cells can look ugly and can be confused with carcinoma!!
